Fire-responsive sprinkler head

ABSTRACT

A fire extinguishing sprinkler head for use with a wide range of extinguishants, such as water and hydrolized ablative gel, which has an expellable plug retained in a discharge opening in the sprinkler head by fire-responsive release means. Upon actuation of the release means, the plug is expelled from the sprinkler head by the pressure of the extinguishant to clear the discharge opening of obstacles which could affect the spray pattern of the extinguishant emitted from the sprinkler head. The plug is released at a predetermined inlet head pressure so that the sprinkler head will not provide the extinguishant to the fire at a pressure which will materially affect the spray pattern from the sprinkler head or adversely influence the spray pattern of other sprinkler heads in the system. The sprinkler head also includes means for modulating the flow of extinguishant in response to the inlet pressure of the extinguishant to retain a predetermined extinguishant spray pattern and to maintain the extinguishant supply pressure to the system at a higher level.

United States Patent Livingston et al.

[ 51 Mar. 28, 1972 [54] F IRE-RESPONSIVE SPRINKLER HEAD [73] Assignee:Factory Mutual Research Corporation,

Boston-Providence Turnpike, Mass.

[22] Filed: Oct. 8, 1969 21] Appl. No.: 864,756

[52] US. Cl. ..i69/38, 169/42 [5 l] ..A62c 37/08 [58] Field of Search..l69/37-42;

[56] References Cited UNITED STATES PATENTS 3,160,212 12/1964 Reid..:.239/583X Werner l 69/ 37 O'Brien et al ..239/487 PrimaryExaminer-Lloyd L. King Attorney-Lane, Aitken, Dunner & Ziems [57]ABSTRACT A fire extinguishing sprinkler head for use with a wide rangeof extinguishants, such as water and hydrolized ablative gel, which hasan expellable plug retained in a discharge opening in the sprinkler headby fire-responsive release means. Upon actuation of the release means,the plug is expelled from the sprinkler head by the pressure of theextinguishant to clear the discharge opening of obstacles which couldaffect the spray pattern of the extinguishant emitted from the sprinklerhead. The plug is released at a predetermined inlet head pressure sothat the sprinkler head will not provide the extinguishant to the fireat a pressure which will materially affect the spray pattern from thesprinkler head or adversely influence the spray pattern of othersprinkler heads in the system. The sprinkler head also includes meansfor modulating the flow of extinguishant in response to the inletpressure of the extinguishant to retain a predetermined extinguishantspray pattern and to maintain the extinguishant supply pressure to thesystem at a higher level.

6 Claims, 5 Drawing Figures E'rqTEgmze I972 SHEET 1 [IF 2 INVENTORSWILLIAM L. LIVINGSTON 8 SEBASTIAN DAVID TINE A ORNEYS P'ATENTEB MR 2 8I972 SHEET 2 BF 2 INVENTORS WILLIAM L. LIVINGSTON 8 SEBASTIAN DAVID TINEFIRE-RESPONSIVE SPRINKLER HEAD BACKGROUND OF THE INVENTION Thisinvention relates to fire-responsive sprinkler heads. More particularly,this invention relates to a sprinkler head which includes an expellableplug which is discharged from the sprinkler head in the event of a fire.Still more particularly, the sprinkler head according to the inventionoperates only when the inlet pressure is above a predetermined minimumand also includes means for varying the effective area of the nozzleorifice as a function of the inlet pressure to maintain the system inletpressure at an effective level and to preserve the spray characteristicof the extinguishant from the sprinkler head.

Fire protection systems are known to the art which provide a supply ofextinguishant under pressure through a suitable conduit network to aplurality of fire-responsive sprinkler heads. Such systems are intendedto retain the extinguishant under pressure for ready release byactuation of a fire-responsive element such as a thennally actuatedfusible member. It is an overall problem in the design of such systemsand in designing fire-responsive sprinkler heads to provide foreffective operation of the system under a reduced extinguishant supplypressure. For example, while a single operative sprinkler head willreceive nearly full operating pressure, successive actuation ofadditional sprinkler heads will cause the inlet pressure to thesprinkler heads to decay, often resulting in an unacceptable operationof the system.

The spray characteristic of the extinguishant from the actuatedsprinkler head is chosen so that the extinguishant survives the flowpath from the sprinkler head to the protected area and so that the sprayprovides a uniform coverage of the area. Thus, spray angles,extinguishant droplet trajectories, extinguishant particle sizedistribution and particle velocity all play an important part inascertaining the effectiveness of the system and are generally variableas a function of the inlet pressure.

Moreover, in a multiple sprinkler head system, the spray patterns areselected to provide optimum coverage of protected areas. In the event ofa fire, the convective effect of a combustion in the protected area willdistort the spray and thus reduce the extinguishing efficiency of thesystem. Under these conditions, a drop in extinguishant pressure mayaffect the performance of the system to such an extent that it ispreferable to leave a sprinkler head unopened rather than further reducethe available extinguishant pressure. Thus, it is a problem in the artto provide a fire-responsive sprinkler head which responds positivelywhen actuated, but which will remain non-responsive when theextinguishant pressure falls below a predetermined minimum.

The drop in the inlet pressure of the system also causes a deteriorationin the effectiveness of the sprinkler heads which have already opened inresponse to the fire. Inasmuch as such opened heads are most likely inthe region of concentrated combustion, it is desirable to maintain thespray characteristics of the actuated sprinkler head although the exitflow rate of extinguishant has been reduced by the opening of additionalsprinkler heads. Thus, there is a need in this art for a sprinkler headwhich can maintain a flow of extinguishant to its assigned area througha wide range of line pressures supplying that head.

The advent of fire protection systems which utilize extinguishants otherthan water imposes still another design constraint on the sprinklerhead. It is, of course, desirable to provide a sprinkler head which maybe used with a wide range of extinguishants to facilitate its use as areplacement for the heads of existing systems, or as a part of a newinstallation which uses an extinguishant different from water, such asfully hydrolized ablative gel. A method of tire protection using agelling agent in the form of a water swellable polymer which is injectedinto a flowing stream of water supplying the sprinkler heads of a fixedextinguishing system upon actuation thereof is disclosed in a copendingapplication, Ser. No. 766,475 filed Oct. 10, 1968 by William L.Livingston and Russell W. Pierce, and assigned to the assignee of thepresent invention.

Thus, it is a principal object to provide a positive actingfireresponsive sprinkler head for use in a fixed sprinkler system.

It is an additional object of the invention to provide a sprinkler headhaving a plug member which is expelled from the sprinkler head when fireresponsive means are actuated.

It is a further object of this invention to provide a sprinkler head inwhich fire-responsive means are provided to retain an expellable memberin the discharge opening of the sprinkler head and, when actuated,permit the member to be expelled from the sprinkler head by the pressureof the extinguishant.

It is still another object of this invention to provide a sprinkler headwhich will release an expellable plug only when the extinguishantpressure is above a predetermined minimum.

It is still a further object of this invention to provide a sprin klerhead having means to modulate the flow of extinguishant in response tothe inlet pressure.

These and additional objects will become apparent from the detaileddescription which follows when perused in conjunction with theaccompanying drawings.

SUMMARY OF THE INVENTION A sprinkler head which overcomes the problemsin the art, as discussed above, and which achieves the stated objects,comprises a body which includes an inlet portion for receiving acontinuous supply of fire extinguishant and a discharge portion defininga discharge opening. An expellable member is disposed within the bodyfor sealing the discharge opening when the sprinkler head is in itsquiescent state. Fire-responsive means, including a spring-biasedtrigger member and a fire-sensing member are provided for securing theexpellable member within the body of the sprinkler head. When thefiresensing member is actuated, the spring-biased trigger rod releasesthe expellable member so that the expellable member may be ejectedthrough the discharge opening of the sprinkler head. An O-ring seal isprovided between the expellable member and the discharge opening and maybe selected so that the member will not be expelled unless theextinguishant pressure exceeds a predetermined minimum. In a preferredembodiment, the sprinkler head also includes pressureresponsive meansfor varying the effective area of the nozzle orifice in the sprinklerhead in response to the extinguishant supply pressure to maintain thespray characteristics of the extinguishant over a wide range ofpressures and to maintain the inlet pressure of' the extinguishant at aneffective level.

The pressure-responsive means include a fixed member secured to amoveable plug by a pair of accordian members to define a cavitycontaining a predetermined quantity of a compressible material. Spinnervanes are located in the body of the sprinkler head to impart arotational characteristic to the flow of the extinguishant through thesprinkler head. The discharge opening may be provided with means forproducing non-circular spray pattern. For example, a plurality ofradially-emanating generally V-shaped notches communicating with thedischarge opening and the exterior of the sprinkler head will produce agenerally rectangular or square spray pattern. In an alternativeembodiment which produces a non-circular spray pattern, a conicaldischarge passage is provided at the outlet of the sprinkler head whichterminates at a surface formed by the intersection of a rightparallelepiped having an axis parallel to the axis of the cone and inwhich the plane cross section of the parallelepiped defines a square ora rectangle.

BRIEF DESCRIPTION OF THE DRAWINGS In the drawings:

FIG. 1 is a view, substantially in cross-section, of the sprinkler headaccording to the invention;

FIG. 2 is a view taken along line 22 in FIG. 1;

FIG. 3 is a view taken along line 3-3 of FIG. 1;

FIG. 4 is a cross-sectional view of an alternate discharge arrangementfor producing a non-circular spray pattern; and

FIG. 5 is a view taken along line 5-5 of FIG. 4.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT In FIG. 1, a sprinklerhead according to the invention is designated generally at and comprisesa body 11 which includes an inlet portion 12, an intermediate portion13, and a discharge portion 14.

The inlet portion 12 of the sprinkler head 10 includes threads 16 forattachment to an outlet conduit (not shown) which forms a part of amulti-head sprinkler system which has a plurality of sprinkler headslocated in a predetermined array with respect to an area to be protectedin the event of a fire. The inlet portion 12 defines an inlet area whichis relatively large compared to the area defined by the dischargeportion 13 to minimize pressure losses at the inlet and to provide apotentially large supply of extinguishant to the discharge portion 13 ofthe sprinkler head 10 when the sprinkler head is actuated. Since fixedfire extinguishing systems, in general, remain inactive for long periodsof time, the inlet area also permits the free passage of solids whichmay have accumulated in the system during the period of its inactivity.

The size of the inlet portion 12 is determined by a number of designcriteria which include such factors as the volumetric availability ofthe extinguishant to the overall system, the static pressure of theextinguishant, the number of heads in the system, the desired flow ratefrom the sprinkler head at that particular position in the system, thecharacteristics of the extinguishant supply system, and the like.Moreover, the overall design characteristics of the nozzle 10, includingthe inlet portion 12, are selected to allow the nozzle to be used with awide range of extinguishants encompassing for example, both water andfully hydrolized ablative gel.

A plurality of spinner vanes 17 are secured, as by integral casting orwelding, to the interior wall of the intermediate portion 13 of thesprinkler head 10. The vanes 17 cause the extinguishant to flow in aspiral streamline through the sprinkler head and thus provide a firstcontrol over the flow characteristics of the extinguishant as it exudesfrom the discharge nozzle. Since the vanes 17 are often necessary tocontrol the flow of extinguishant from the relatively large inletopening discussed above, the number of vanes and their physicalcharacteristics are also determined by the factors discussed withrespect to the determination of the area of the inlet opening. Forexample, a relatively long spiral surface 18, acting on theextinguishant through a large arc, for example 180, will impart agreater rotational characteristic to the flow of extinguishant than willa shorter spiral path acting through a lesser arc.

In its quiescent or unactuated state, .the sprinkler head 10 includes arod 20 secured to an expellable plug designated generally at 21 whichforms a watertight seal with the discharge opening 22 defined by thedischarge portion 14 of the sprinkler head 10. In the embodimentdepicted, the plug 21 includes an annular member 24 having a diameternearly equal to the diameter of the discharge opening 22. An annulargroove 25 is located in member 24 to accommodate a sealing member 26. Itshould be noted that the plug 21 may either be a separate member securedto the rod, as shown, or may form an integral part of the rod.

Means, designated generally at 28 and responsive to the presence of afire, such as by thermal actuation, are provided for securing the rod 20within the sprinkler head 10 during its rest state. A trigger rod 30includes a protruding portion 31 located in an opening 32 defined nearthe distal end of the rod 20. When the trigger rod 30 is connected tothe member 20 as shown, or is secured to rod 20 by an equivalentconnection, it acts as an effective means for retaining rod 20 and plug24 within the sprinkler head.

A retaining member 35, best seen in FIG. 2, defining an axial opening 36for receiving the distal end 33 of rod 20 and a lateral opening 37 foraccommodating the protruding portion 31 of the trigger rod 30 isprovided to impart structural integrity to the connection between therod 20 and the trigger rod 30 without greatly affecting the flowcharacteristics of the extinguishant through the sprinkler head. Theretaining member 35 may be integrally cast within the sprinkler head 10or may be formed separately and secured to the interior of the sprinklerhead 10 by means known to the art, such as by welding a portion thereofto the spinner vanes 17, or by the judicious use of fasteners.

A threaded nipple member 40 defining an opening 41 is engaged withamating threaded opening 42 located in a wall portion 43 positioned atthe transition between the inlet end portion 12 and the intermediateportion 13 of the sprinkler head 10. The wall portion 43 may be providedwith an increased wall thickness as shown to provide additional strengthif desired. The opening 42 is sized to accommodate the trigger rod 30 inits quiescent state and to permit axial movement of the trigger rod 30therethrough in the event of a fire, as will be discussed.

A coupling member 45 defining an interior cavity 46, a first threadedopening 47 and a second threaded opening 48 is threadedly engaged withnipple 40. Preferably, openings 41, 47 and 48 are disposed about acommon axis to permit free axial travel of the trigger rod 30 when thesprinkler head is actuated.

A first annular member 50, such as a washer, is provided about anintermediate portion of the trigger rod 30 and rests against a surface52 defined by the anterior end of nipple 40. A spring 54, also locatedabout an intermediate portion of the trigger rod 30 is contained withinthe cavity 46 of the coupling member 45 and includes a first end 55abutting the first annular member 50 and a second end 56 abutting asecond annular member 57, such as a washer, located about the triggerrod 30.

A third annular member 59 provides a shoulder for retaining the triggerrod in its illustrated position-in position in the absence of a fire andto retain the spring 54 in a compressed, or biased state. The annularmember 59 may constitute an integral part of the trigger rod 30, or maybe eliminated if the head portion 60 of the trigger rod 30 has adiameter which is sufficiently great to provide a shoulder against whichthe annular member 57 may rest.

A conventional fire detector, designated generally at 62, comprises ahousing 63 secured to a base 64 having a threaded portion 65 in athreaded arrangement with the mating threads in the opening 48 of thecoupling member 45. The base 64 and the portion of housing 63 adjacentthereto together define an opening 67 for receiving the head portion 60of the trigger rod 30.

It is an advantage of the system to use conventional fire detectors foreither water sprinkler systems or ablative gel sprinkler systems sincesuchdetectors are presently approved by fire protection agencies,insurance companies, trade associations and other interestedauthorities. In this manner the accumulated experience and the low costof the conventional fire detectors may be used to great benefit.However, this system is not confined to actuation by either theillustrated thermallyactuated device or by known fire detection elementssince the fire-preventative characteristics of ablative gel systems maydictate certain modifications in the opening characteristics of thesensing element, in response to its controlling parameter, e.g. heat,flame, smoke and the like, to utilize the benefits of the ablative gelsystems to full advantage. For example, the performance of ablativewater systems may permit later actuation of the fire detector to permitalternate forms of fire protection to be used first, while yet providingan improved margin of safety. Thus, it may be possible to avoidactuation of the system by nuisance and small fire operations withoutcompromising the safety of the premises.

A fire-responsive element designated generally at 69, comprises a firstfusible portion70 and a second fusible portion 71 mounted in the housing63 between a first supporting member 72 and a second supporting member73. The element 69 is designed to forsake its structural rigidity at apredetermined temperature, thus permitting the head portion 60 of thetrigger rod 30 to extend axially under the influence of the spring 54thereby freeing the rod 20 from its restraining influence on the triggerrod 30. In the absence of a fire or other thermal actuation, thetransverse shear strength of the fusible link portions 70 and 71 issufficiently great to withstand the extensible force of the spring 54acting on the trigger rod 30 thus to retain the trigger rod 30 in itsquiescent state.

A fusible nut 75, responsive to a predetermined temperature, is alsolocated adjacent to the plug 21 in the discharge opening 22 of thesprinkler head 10. The fusible nut 75 provides a safeguard against theexpulsion of rod 20 in the event that the fusible link 69 isinadvertently actuated and also prevents an accumulation of dirt andgrime in the discharge opening 22 which may otherwise afiect theexpulsion of rod 20 from the sprinkler head in the event of fire.

If both the fusible link 69 and the fusible nut 75 have been thermallyactuated, the sprinkler head is actuated to permit the extinguishant tobe discharged from the discharge opening 22 in a predetermined pattern.A fusing of the portions 70 and 71 of the fire-responsive element 69releases the retaining force exerted against the head portion 60 of thetrigger rod, permitting the rod to be axially displaced by the force ofthe spring 54 exerted through member 57 against the shoulder of annularmember 59. The limited axial movement of the rod 30 is sufficient tofree the protruding member 31 from its engagement with the opening 32 inexpellable rod 20.

The pressure of the extinguishant against the plug 21 causes the plugand rod to be expelled from the discharge opening 22. As an alternative,a chain or wire may be secured to the rod 20 to permit its ready releasewithout allowing the rod 20 to fall to the surface below the sprinklerhead 10. As another alternative, the tongue and groove relationshipbetween the protruding member 31 and the opening 32 may be replaced withother suitable releasable connections. For example, the distal end 38 ofthe rod 30 may be bifurcated wherein the bifurcations are positioned indiametrically-opposed recesses in the distal end of the rod 20. In anyevent, the spring 54 must have sufficient strength to overcome thefrictional engagement of the end connections used as well as thefrictional engagement of the rod 30 with the openings 41 and 67 by asuitable margin of safety.

It is a feature of the invention that the pressure necessary to expelthe plug 21 from the discharge opening 22 may be selectable inaccordance with the needs of the system. In a multiple sprinkler headsystem, the placement of the heads is determined in part by the spraycharacteristics of the nozzle. In turn, the spray characteristics are inlarge measure a function of the pressure of the extinguishant suppliedto the noule. Thus, the size, physical characteristics or material ofplug 21, or in particular, the seal 26, may be selected to prevent theexpulsion of the plug member until a minimum extinguishant pressure isavailable, even after the trigger mechanism has been released asheretofore described. The minimum pressure at which the head may beopened is determined by the pressure necessary to produce an acceptableextinguishant spray from the sprinkler head and at which pressure,actuation of the sprinkler head would have an adverse effect on thespray patterns or other sprinklers in the system which have alreadyopened.

It is another feature of the invention to provide means to modulate theflow of extinguishant from a predetermined maximum to some minimum flowwhich will continue to produce an acceptable spray characteristic fromthe sprinkler head and maintain an inlet pressure to the system whichpermits satisfactory operation of previously-opened sprinkler heads.Thus, a pressurized bellows assembly, designated generally at 76,comprises a fixed member 77 secured to a pair of accordian members 78and 79 secured respectively to an axially-displaceable, movable member80.

Accordian members 78 and 79 define a closed annular cavity 85 whichcontains a predetermined quantity of compressible material, for example,an inert gas. When the pressure of the extinguishant at the inlet to thesprinkler head is at its maximum for the system, for example, when noother sprinkler heads in the array have been actuated, the volume of theclosed cavity 85 is at a minimum since the pressure within the cavityseeks to balance the inlet pressure of the extinguishant. Under thatcondition, the distance between the fixed member 78 and the plug member80 is at its minimum, permitting a maximum flow of the extinguishant tothe nozzle orifice 82 through the passage designated generally at 83.When the inlet pressure of the extinguishant'decreases, for example,from increased demands on the system by the actuation of other sprinklerheads, the flow modulating assembly 76 operates to achieve a hydrostaticbalance. Since the quantity of compressible fluid in cavity 85 is fixed,the volume of cavity 85. increases until the pressure exerted fromwithin the cavity 85 is equal to the pressure of the extinguishant onthe exterior of the cavity.

Because the cavity 85 is incapable of circumferential expansion, thedistance between the fixed member 78 and the plug member 80 increases toa maximum, thus constricting the effective discharge area of the nozzleorifice 82. When the area of the nozzle orifice 82 is thus constricted,the flow rate of the extinguishant is reduced, so that the spray patternof the extinguishant from the sprinkler head is maintained and the inletpressure to the sprinkler head is increased to maintain a higher inletpressure to the overall system.

It is another feature of the invention that the flow modulating assembly76 and the nozzle orifice 82 may be designed to eliminate the fiow ofextinguishant from the sprinkler head 10 in the event that the inletpressure falls below a predetermined level. Thus, the total demand forextinguishants from the supply system may be maintained within thecapabilities of the system whether the flow discharge rate is modulatedor eliminated.

Still another significant advantage of the sprinkler head according tothe invention resides in the fact that the invention may be used for awide range of extinguishants such as from water to fully hydrolizedablative gel. This feature lends an added dimension to existing systemswhich may ultimately be converted to an ablative water extinguishant, orfor use in ablative water systems having a serve capability which useswater as the extinguishant.

The conventional wisdom relating to the present-day sprinkler headsincludes the knowledge that spray patterns other than circular may bedesirable to minimize the unprotected floor area beneath the sprinklerhead. FIGS. 3 through S indicate structural features of or additions tothe base of the discharge portion 14 of the sprinkler head to providerectangular or square extinguishant flow patterns.

lnFIG. 3, a plurality of radially extending, generally V- shaped notches89 are in communication with the discharge opening 22 and with theexterior of the sprinkler head. The extent of the flow pattern isdetennined by the maximum width of the notch, the depth of the notch,the flow rate of the extinguishant and the like.

FIG. 4 depicts an alternative embodiment of the discharge portion,designated at 90, equivalent to the discharge portion 14 of a sprinklerhead 10 according to the invention. The discharge portion 90 includes acavity defined by a cylindrical upper portion 91 and a lower portion 92.Upper portion 91 is defined by a cylindrical surface which merges into aflow passage defined by a cone which has been intersected by a rightparallelepiped having an axis parallel to the axis of the core. Thus, aplurality of surfaces 93 are generated which define portions of planeswhich are also generally parallel to the axis of the conical portion 92.Each of the surfaces 93 also defines an arc-like segment 94 having anapex defined by the shortest line on the conical surface of the conicalportion 92 from the cylindrical surface 20. The structure thus describedis capable of producing a non-circular spray pattern.

Thus it will be appreciated that by this invention there is provided ahighly effective sprinkler head which may be used with a wide range ofextinguishant by which the aims and the objects of the invention areachieved.

What is claimed is:

l. A sprinkler head comprising a body having an inlet portion forreceiving a supply of fire extinguishant at an inlet pressure and adischarge portion defining a discharge opening; plug means secured tosaid body to close said discharge opening when said sprinkler head is inits quiescent state for preventing a flow of extinguishant through saiddischarge opening; a trigger member having a portion thereof inengagement with said expellable means when said sprinkler head is in itsquiescent state for locking said expellable means in said body; afusible link; a spring for freeing said trigger member from saidexpellable means when said fusible link is actuated; a nipple memberconnected to said housing and defining an opening for receiving saidtrigger member; a coupling secured to said nipple member and defining acavity, said spring being located about said trigger member in saidcavity between said nipple member and a shoulder defined on said triggermember; a housing for said fusible link; and a base secured to saidhousing and to said coupling member; said base and said I housingdefining an additional opening, a portion of said ,trigger member beinglocated in said additional opening and being retained in a firstposition by said fusible link, said trigger member adapted to assume asecond position axially displaced from said first position when saidfusible link is actuated, whereby said expellable means is ejected fromsaid sprinkler head by the force of the inlet pressure of said fireextinguishant acting on said expellable means.

2. A sprinkler head comprising a body having an inlet portion forreceiving a supply of fire extinguishant at an inlet pressure, adischarge portion defining a discharge opening, and a nozzle orifice;expellable means for preventing a flow of extinguishant through saiddischarge opening when said sprinkler head is in its quiescent state;fire-responsive means, including a fire-sensing member for locking saidexpellable means in said body when said sprinkler head is in itsquiescent state and unlocking said expellable means when saidfire-sensing member is actuated to permit the ejection of saidexpellable means from said sprinkler head by the force of the inletpressure of said fire extinguishant acting on said expellable means; andpressure-responsive means for varying the efiective area of said nozzleorifice as a predetermined function of the inlet pressure, said pressureresponsive means comprising a fixed member, a moveable membercooperating with said nozzle orifice to vary the effective area thereof,and a plurality of accordion-like members secured to said fixed memberand said moveable member; said fixed member, said moveable member, andsaid plurality of accordion-like members defining a cavity adapted tocontain a predetermined quantity of compressible fluid, whereby thevolume of said cavity varies as a function of the inlet pressure so thatsaid moveable member controls the effective area of said nozzle orificein such a manner that a predetermined extinguishant spray pattern iseffectively maintained for extinguishant inlet pressures which vary froma predetermined maximum to a predetermined minimum.

3. A sprinkler head as defined in claim 2 wherein the flow ofextinguishant is caused to cease at said predetermined minimumextinguishant inlet pressure by the structural cooperation of saidmoveable member and said nozzle orifice.

4. A discharge head for use in a fixed fire extinguishing systemcomprising a body member having an inlet for connecting to a source ofextinguishant and an outlet for permitting discharge of saidextinguishant from said body member, said body member defining anextinguisha'nt flow path between said inlet and outlet, releasable meansnormally disposed in said body member for preventing fluid flow fromsaid outlet, a latching member engaging said releasable means in saidbody member for retaining said releasable means in said outlet, aportion of said latching member extending out of said flow path, andcontrol means cooperating with said portion of said latching member andresponsive to a predetermined fire situation in the vicinity of saidbody member for permitting the disengagement of said latching memberfrom said releasable means and the release of said releasable means fromsaid outlet.

5. The discharge head of claim 4 wherein said releasable means comprisesa rod engaged by said latching member and a plug member connected tosaid rod and-extending in said outlet.

6. The discharge head of claim 5 wherein said control means in in theform of a fusible link, and wherein said latching member is springloaded and is connected between said rod and said fusible link so thatsaid rod is released upon collapse of said fusible link in response tosaid predetermined fire situation.

1. A sprinkler head comprising a body having an inlet portion forreceiving a supply of fire extinguishant at an inlet pressure and adischarge portion defining a discharge opening; plug means secured tosaid body to close said discharge opening when said sprinkler head is inits quiescent state for preventing a flow of extinguishant through saiddischarge opening; a trigger member having a portion thereof inengagement with said expellable means when said sprinkler head is in itsquiescent state for locking said expellable means in said body; afusible link; a spring for freeing said trigger member from saidexpellable means when said fusible link is actuated; a nipple memberconnected to said housing and defining an opening for receiving saidtrigger member; a coupling secured to said nipple member and defining acavity, said spring being located about said trigger member in saidcavity between said nipple member and a sHoulder defined on said triggermember; a housing for said fusible link; and a base secured to saidhousing and to said coupling member; said base and said housing definingan additional opening, a portion of said trigger member being located insaid additional opening and being retained in a first position by saidfusible link, said trigger member adapted to assume a second positionaxially displaced from said first position when said fusible link isactuated, whereby said expellable means is ejected from said sprinklerhead by the force of the inlet pressure of said fire extinguishantacting on said expellable means.
 2. A sprinkler head comprising a bodyhaving an inlet portion for receiving a supply of fire extinguishant atan inlet pressure, a discharge portion defining a discharge opening, anda nozzle orifice; expellable means for preventing a flow ofextinguishant through said discharge opening when said sprinkler head isin its quiescent state; fire-responsive means, including a fire-sensingmember for locking said expellable means in said body when saidsprinkler head is in its quiescent state and unlocking said expellablemeans when said fire-sensing member is actuated to permit the ejectionof said expellable means from said sprinkler head by the force of theinlet pressure of said fire extinguishant acting on said expellablemeans; and pressure-responsive means for varying the effective area ofsaid nozzle orifice as a predetermined function of the inlet pressure,said pressure responsive means comprising a fixed member, a moveablemember cooperating with said nozzle orifice to vary the effective areathereof, and a plurality of accordion-like members secured to said fixedmember and said moveable member; said fixed member, said moveablemember, and said plurality of accordion-like members defining a cavityadapted to contain a predetermined quantity of compressible fluid,whereby the volume of said cavity varies as a function of the inletpressure so that said moveable member controls the effective area ofsaid nozzle orifice in such a manner that a predetermined extinguishantspray pattern is effectively maintained for extinguishant inletpressures which vary from a predetermined maximum to a predeterminedminimum.
 3. A sprinkler head as defined in claim 2 wherein the flow ofextinguishant is caused to cease at said predetermined minimumextinguishant inlet pressure by the structural cooperation of saidmoveable member and said nozzle orifice.
 4. A discharge head for use ina fixed fire extinguishing system comprising a body member having aninlet for connecting to a source of extinguishant and an outlet forpermitting discharge of said extinguishant from said body member, saidbody member defining an extinguishant flow path between said inlet andoutlet, releasable means normally disposed in said body member forpreventing fluid flow from said outlet, a latching member engaging saidreleasable means in said body member for retaining said releasable meansin said outlet, a portion of said latching member extending out of saidflow path, and control means cooperating with said portion of saidlatching member and responsive to a predetermined fire situation in thevicinity of said body member for permitting the disengagement of saidlatching member from said releasable means and the release of saidreleasable means from said outlet.
 5. The discharge head of claim 4wherein said releasable means comprises a rod engaged by said latchingmember and a plug member connected to said rod and extending in saidoutlet.
 6. The discharge head of claim 5 wherein said control means isin the form of a fusible link, and wherein said latching member isspring loaded and is connected between said rod and said fusible link sothat said rod is released upon collapse of said fusible link in responseto said predetermined fire situation.